Radar scanner unit



March 6, 1951 1'. l. MOSELEY 2,544,433

RADAR SCANNER UNIT Filed May 27, 1946 8 Sheets-Sheet l Q r s M I 4 INVENTOR.

March 6, 1951 T. I. MOSELEY RADAR SCANNER UNIT Filed May 27, 1946 8 Sheets-Sheet 2 kw Q m2 mm INVENTOR. 7bm/m50/2/T/V05e/ ATTOPNEYE 8 Sheets-Sheet 3 Filed May 27, 1946 k 5 R Y Z M m 4 M Y r I N 0 w m h m mm mm wh hm mm .E. mo mm mm hm mm March 6, 1951 T. 1. MOSELEY 2,544,433

RADAR SCANNER UNIT Filed May 27, 1946 8 Sheets-Sheet 4 HI ll Q m b a, 3 n w v g 3 3 5 ul N 3 N 9| a 3 2 7, r2 w n \n I 2 3 I 8 a g E w L I In L? INVENTOR. 7m/zrzsa/z/ffi/ose/ey BY March 6, 1951 T. I. MOSELEY 2,544,433

RADAR SCANNER UNIT Filed May 27, 1946 8 Sheets-Sheet 5 INVEN r012. 75/77/0750 Naif/9y March 6, 1951 T. I. MOSELEY 2,544,433

' RADAR SCANNER UNIT Filed May 27, 1946 8 Sheets-Sheet 6 Fig. 6

' I54 I Sl me l5l I49 I52 I45 0 Q G 0 0 0 INVENTOR. 75/77/0250/1 [Maia/6y BY March 6, 1951 'r. 1. MOSELEY 2,544,433

RADAR SCANNER UNIT Filed May 27, 1946 8 Sheets-Sheet T Fig. 7

I INVENTOR. 75/77/m50/2 f Maia/6y WWW A T TOP/W545 March 6, 1951 T; I. MOSELEY 2,544,433

RADAR SCANNER UNIT Filed May 27, l946 8 Sheets-Sheet 8 Fig. 6

I INVENTOR. 75/77/0750 Max/6y BY ATTOPNEY? Patented Mar. 6, 1951 UNITED STATES PATENT OFFICE RADAR SCANNER UNIT Tomlinson I. Moseley, Atherton, Calif.

Application May 2'7, 1946, Serial No. 672,462

' '1 Claims. (01. 250-3s.s5)

This invention relates to radar equipment and in general has for its object the provision of a rotary and oscillatory reflector and feed horn arranged continuously and progressively to scan a conical zone with a radio frequency wave and a generator and a potentiometer operating in synchronism with the antenna and reflector for continuously indicating on a screen, the angular position of the reflector with reference to its axis of rotation and the angular position of the reflector with respect tothe axis of oscillation.

A further object of the invention -is the provision of a simple and effective driving mechanism for simultaneously rotating and oscillating the parabolic reflector of a radar scanner and for actuating a generator and potentiometer in synchronism with the movement of the reflector.

Another object of the invention is the provision of a frame on which a parabolic reflector is mounted through a universal joint and which is so constructed and counterbalanced that it can readily be brought into dynamic balance with respect to its axis of rotation aswell as with respect to its axis of oscillation.

Still another object of this invention is the provision of a radar scanning unit having a wave guide conduit, the interior of which within limits, can be maintained at any predetermined gaseous pressure irrespective of the pressure external thereto.

More specifically the object of this invention is the provision of a dynamically balanced scanning device including a frame in which a spindle is journaled for rotation by a motor through a suitable gear train. Swiveled to the spindle is a dynamically balancing head bracket on which is mounted a parabolic reflector provided with a feed horn extending along the axis of the reflector. Rotatably disposed within the spindle is a tubular wave guide terminating at its forward end in a goose neck through which it communicates with the feed horn. Slidably mounted over the wave guide is a reciprocating rack sleeve provided at its forward end with a rack operatively associated with a pinion secured tothe head bracket so that the reciprocating movement of the sleeve will cause the reflector and its feed horn to oscillate or nod.- Reciprocation of the rack sleeve is produced by the gear train through a clutch controlled crank arm. Normally the reflector is made to nod through a relatively wide angle (:60) but when a target has been brought into a specific pdsition on the screen, it is desirable to restrict the angle of nod so that scanning takes place only in a zone immediately surrounding the target. Conveniently the nodding of the reflector is restricted by means of a solenoid operated latch, the solenoid being under the remote control of an operator. Mechanically coupled to the reciprocating rack sleeve are the arms of a potentiometer having an elevation section and an azimuth section connected across both phases of a two-phase generator driven by the scanner motor. The position of the two potentiometer arms determines the amplitude of both phases of, the generator, the amplitudes of these phases being utilized to indicate the relative elevation and azimuth of the reflector through a suitable electrical circuit forming per se no part of the present invention. p i

The invention possesses other advantageous features, some of which with the foregoing will be set forth at length in the following description where that form of the invention, which has been selected for illustration in the drawings ac companying and forming a part of the present specification is outlined in full. In said drawings, one form of the invention is shown, but it is to be understood that it is not limited to such form, since the invention, as set forth in the claims, may be embodied in a plurality of forms.

Fig. 1 is a perspective view of a radar scanner.

embodying the objects of my invention.

Fig. 2 is a side elevation of the scanner illus-' trated in Fig. 1 with portions broken away better to illustrate its construction and with its reflector assembly shown in a full nod position.

Fig. 3 is a longitudinal horizontal mid-section of the scanner shown in Fig. 1 except for the reflector and generator which are shown in plan.

Fig. 4 is a partial vertical mid-section of the scanner illustrated in Fig. 1 particularly showing the construction of its main gear housing, spindle housing, reciprocating rack sleeve and pinion, and rack sleeve driving mechanism.

Fig. 5 is a rear end elevation of the scanner with portions broken away better to illustrate the construction ofits air pump.

Fig. 6 is a rear end elevation similar tothat illustrated-in Fig. 5 but showing in sectionthe mechanism by which reciprocating motion is, imparted'to the rack sleeve from the gear train.

Fig. '7 is an interior view of the gear train looking rearwardly, with the gear housing removed and with portions of the gears broken away bet-' ter to illustrate its construction.

Fig. 8 is a schematic. top-plan view of the rack sleeve and oscillating mechanism, the potentiometer drive and solenoid stop mechanism.

:The scanner shown in the various figures above and flanged main spindle E5, the spindle being.

sealed to the housing cover 2 by a seal ring H} and to the housing I by a seal ring l8. screwed? to the main spindle [6 are a plurality vof periph-.

erally spaced balancing washers l9 by'whichthe' spindle and its associated partscantbebrought into dynamic balance. Screwed over the forward end of the spindle I6, is a bearing retaining ring and provided in the housing 4 adjacent to and communicating with r the -ballbearing I 5, is a lubricating-nipplel l; k

The housing cover 2 is formed with a forwardlyextending boss 22" in which is 1 mounted a pair of=i ball bearings 23 and 24-;--held in place by a retainer- 25 (F-i'gp lis Mounted in the ball bearin s 23- and '24' is the shaft- 26 61 a motor drive pin-ion 27; the rear end of'th'eshaft zfi being keyed to the-forward end of-the'motor shaft 28. Sur-' rounding -the rearward' end- (left hand endas shown in Fig. 4) of theshaft 2S=is a sealring 29" foFsealin'g the shaft'to" the housingcover 2. Meshing with lthe=-pinion 27' is e a main gear 3 I} which"; together With' a concentric auxiliary gear- 32, is locked to the main spindle iB-"byawvasherj 33"and a-lo'ck nut 34. Formed in thehou'sing cover 2 in alignmentwith' the generator-I is a boss-35in which is mounted a pairof ball bearings 36-and 31, and journaled in these bearings is the hollow shaft 38' of'a generator drive gear 39', the shaft 38 being keyed to the shaft of the generator: 1; sink lz-g formed in the left face of-th-hOusing cover-Lisa sealring 43, by which'the hollow shaft 3 8 isseale'd' to"th'e hou'sing cover 2.' The gear 39 meshes with the auxiliary gear 32 and is therefore driven by the motor 6*th'rough the main gear- 3Iand the pinion 21. Also in mesh" withthe-auxili'ary gear 32 isa clutchdrive gear 44% mounted on a 1 hollow shaft 45, --the shaft 45-- being'journaled in a' pairof ball bearings 46 and 41 mounted in-a boss--48 extending-forwardly of the-housing cover 2. Secured over the'forward end of the boss 48' is a ball bearing'retainer 49. Keyed to the hollow haft 45 is a worm gear shaft 5l journaled"in a-pair oflongitudinally spaced ball bearings 52 and 53, the ball bearingsbeing mounted in a longitudinally extending chamber- 54 formed in the clutch housing 3. Disposed between the chamber 54 and the shaft 5! is a seal ring'55, and closing the left endof the'chamber Accommodated within a counter- 54' "(as viewed in Fig. 4) is-a cap 56 bolted to casting 3 by means"ofbolt"51" Provided'intermediate the ends of" shaft 5 i is a worm gear 58, the=i-function ofrt'which will be presently "de scribedz- 'i Bolted to. the right end of'thei-main spindle-l6;

isa head pivot bracket 6 i in which is mounted a pairzof transversely spaced ball bearings C--2 and 63 and towhich is'screwed a plurality of: balancing washers fill symrnetricallydisposed about its periphery. Journaleddn'the bearings'filand 63 is'an oscillating: pinion sleeve'64; provided on its periphery with' a pair of transversely spaced pinions :55. and::66-a Disposedir'within:thersleve 64, and having a force fit therewith is an oscillating tube body 61, provided with an antenna feed connection 68, extending forwardly through an opening 69, formed in the sleeve 64 along the axis of the main spindle (6. Fixed to the sleeve 64 by means of rearwardly extending ears 70 is a U-shaped head bracket H to which is bolted a parabolic reflector l2, and bolted to the reflector 12 coaxially therewith and to the connection 68 is'the1base'73'of a feed \horni74. The: feed horn terminates in a cup 15 provided on its rear face with a pair of opposed windows through which a radio frequency wave or signal can pass to and fromtthereflector. It should be particularly noted that the 1egs 76 of the U-shaped bracket H extend rearwardly of and on either side of the oscillatingrtubebodyffi'f and are provided with a plurality of balancing washers 11 (Fig. 3) so that theentire oscillating assembly can be brought into dynamic balance about its center of movement.

Mb'unted in the" rear face of the clutch bracket I 3 (see Figs. 3 and 4)'ov'er a gasket is a bearing housing .Sl'in which is seated a ball bearingand air seal 85. Fixed to the rear face of'the bearing housing 8|'-and' sealed-withthe oil and 1 air seal 851s a rightangle wave-guide connec tionfor connecting'the scannerwith a suitable source of radio frequency energ-y.- Disposed across the connection-86 is a resonance ring 81 and screwed in (its'rean wall is a tuning button 88. Airesonanceringiisra 'filter-iforan unsymmetrical mode resulting from a rectangular to" circularztransition 'as-is-found in a rotary joint. Thus, whenever a transition is made-from a rec'- tangular guide to a circular-guide'both the TEi-,1 and IMoji modes are excited. The TMo,'1 mode is a symmetrical modewhich allows relative rotation of the upper: and lower sections of the rotary joint'with a minimum variation in power.

However, the TE1',1 mode is an unsymmetrical" mode which causes a variationof power with r0- tation. The resonancering 81 isintroduced into the wave guide to filte'r' out the unwanted TE1;1 mode.

Secured Within the sleeve 83'is'the'rear end of a wave guidetube' 89 "having its' forward end secured and sealed to the inner end of a goose neck wave guide fitting 9|; The outer end'of the fitting 9! is sealed to the oscillating tube body Gland head pivot bracketfi l" by a seal ring 92. Screwed to the fitting 9| along the axis of the wave guide tube 89 isa tuning button 93 and extending across its outer end is a resonance ring 94.

From the above description it may be seen that a radio frequency energy wave or signal initiated from any suitable source can be made to traverse the wave guide connection 86,'the wave guide tube 89,'the goose neck fitting 9|, the oscillating tube'bo'dyfiland the feed horn M;

The antenna cupl5 directs the" waverearwardly to the reflector 12' which then reflects the wave outwardly in a divergentbeam'having a 'solid angle of about 6." When the'scanner is on targe ithe returning.echo wave or signal is picked up by the reflector and traverses in' reverse, the path above described; During operation, the tube 89; fitting 9|, tube body'fil, reflector 12,'feed horn'14,'and cup 15"all rotate as an integral unit with the main spindle l6 which, as above described, is rotated by-theumotor. 6 through the inion:21.and the main-gear 3!. However; since the pinion sleeve 84 is journaled in the head pivot bracket 6| and since the reflector 12 and feed horn 14 are formed as integral units with the sleeve 64, the reflector 12 and feed horn 14 in addition to being free to rotate about the axis of the main spindle it, are free to oscillate or nod about the axis of pinion sleeve 64. By oscillating these members through a plane angle of 60 on either side of the spindle axis, and simultaneously rotating them about the spindle axis, the 6 radio frequency energy beam can be made continuously and progressively to scan a solid angle of 120, four times during each complete nod cycle.

Oscillation or nodding of the reflector and its associated parts is effected through a reciprocating mechanism including a rack sleeve IOI having a sliding fit over the wave guide tube 83 and with which the sleeve IOI rotates. Secured to the forward end of the sleeve IOI on one side thereof is a pair of longitudinally extending laterally spaced racks I02, one in mesh with each of the transversely spaced pinions 65 and 66 carried by the pinion sleeve 64. To balance the weight of the racks I02, the sleeve rack is provided on its side diametrically opposite the racks I02, with a pair of laterally spaced balancing members I03 (see Fig. 4). The reciprocation of the sleeve rack with its racks I02 in mesh with the pinions 65 and 66 therefore produces the required oscillation of the reflector 12 and its associated parts.

Disposed over the left end of the sleeve rack I (Figs. 3 and 4) is a thrust bearing housing I05 provided with a laterally extending slide lug I06 and with an opposed forked guide receiver I01. Fixed to the sleeve rack MI in abutment with a shoulder I08 formed thereon is a thrust bearing rack I09 and abutting the rack I09 is a sleeve Ill. Mounted on either side of the rack I 09 and having running contact therewith are looking rings H2 and H3 and located between these two locking rings is a spacing ring II4. Disposed on either side of the rings H2 and H3 are gaskets I I5 and I I6, the assembly so described being held together by a split locking ring I I1.

Seated in the forked guide receiver I01 (Fig. 1) is a guide bushing Il8 slidably mounted on a guide rod II9, extending between and secured to the main housing cover 2 and to the rear face of the clutch bracket 3.

Bolted to the side face of the clutch bracket 3 (see Figs. 3, 5 and 6) is a potentiometer bracket I2I formed with an undercut runway or channel I22 and provided on the lower face of its rear end with an upwardly recessed potentiometer seat I23 to which the potentiometer II is bolted. Slidably mounted in the channel I22 is a potentiometer slide rack I24, and bolted to the forward end of this slide rack is a slide lug I06 (Fig. 3). Mounted on the potentiometer rack I24 is an upwardly extending connecting rod pin I25 on which one end of a longitudinally adjustable connecting rod I26 is journaled (Fig. 3). Secured to the opposite end of the connecting rod by a pin 121 is a crank I28 (Fig. 6) mounted on the lower end of a clutch shaft I29 of the clutch unit 8.

As shown in Fig. 6, the clutch unit 8 includes a housing I3I provided at its upper end with a flange I32 by which it is bolted to the clutch bracket 3. Mounted in the upper and lower ends of the clutch housing I3I are ball bearings I33 and I34 by which the clutch shaft I29 is journaled in the clutch housing, the bearing I34 being seated against an internal flange I35. Seated on the upper face of the flange I35 is a seal ring I38. Journaled on the shaft I29 somewhat below its upper end is a worm gear I31 arranged to mesh with and be continuously driven by the worm 58 formed on the shaft 5| (Figs. 2, 4 and 6). Screwed to the upper face of the worm gear I31 is a friction cone I38 and slidably keyed to the upper end of the shaft I29 is a conical clutch plate I39. Threaded over the upper end of the shaft I29 is a nut MI and disposed between the nut I 4| and the upper face of the clutch plate I39 is a spring I42 for continuously holding the clutch plate in frictional driving engagement with the friction cone I38.

As a result of the construction just described it will be seen that the worm 58 is driven by the motor 6 through the motor drive pinion 21, the auxiliary gear 32 and the clutch drive gear 44; that the worm 58 continuously drives the Worm gear I31 and that unless there is slippage between the friction cone I38 and the clutch plate I39, the

rotation of the worm gear I31 will be imparted to the shaft I29 and to the crank I28 carried on its lower end. Through the action of the connecting rod I26, the rotary movement of the crank I28 is translated into a reciprocatory movement of the potentiometer rack I24 and the thrust bearing housing I05 to which it is attached. Since the sleeve rack IOI is fixed to the housing I05, it will reciprocate with the potentiometer rack to cause the reflector 12 and its associated parts to nod or oscillate as above explained while on search for a target.

Sometimes it is desirable to limit scanning to a relatively small solid angle in the order of 15. This results is produced by locking the potentiometer slide rack I24 against further reciprocation in such a position that the reflector 12 is held at an angle of about 3 off the axis of rotation. To this end the solenoid 3 is provided with a soft iron plunger I45 normally held in its elevated position by a spring I46. Mounted on the base I41 of the solenoid is a bifurcated bracket I48 on which is fulcrumed a latch or stop lever I49, the inner end of the stop lever being provided with a slot I5I for the reception of a pin I52 carried by the forked upper end of the solenoid plunger. Normally the free end of the stop lever I49 is in its depressed inactive position. However when the solenoid coil is energized, the plunger is drawn downward, thereby causing the free end of the stop lever to swing upwardly into engagement with the rear end of the slide rack 24 and to thereby limit its stroke and the amplitude of nod of the reflector 12. It is to be noted that when this occurs slippage takes place between the friction cone I38 and clutch plate The potentiometer slide rack I24 in addition to imparting reciprocatory movement to the rack sleeve IOI is arranged to mesh with a pinion I6I fixed to the potentiometer shaft I62. Mounted on. the shaft I62 are a pair of diametrically opposed coplanar and electrically independent potentiometer arms I63 and I64, arranged respectively to traverse over electrically independent resistance windings I65 and I 66. Each of these windings subtends an angle of 170 and each of the con tact arms travels over an arc of corresponding to the full 120 nod travel of the reflector. Although per se, the electrical circuit associated with scanner now under consideration forms no part of the present invention, it should be noted that the contact arm I63 and I64 traverse (back and forth) their respective potentiometer windings- I 65;; and .:I 65 ;-':inrsynchronismr:with.L the noddingsof;the'reflector 12;;that one of these.

two-phase generator I, the position of contact arms I63 and lfi tcan be made to determine the amplitude'of these phases.- Bymeans of a suitable receiver-amplifier unit this electrical information can be interpreted and presented visually on the face ofan indicator tube or screening; in a knownmanner, so-as to-indicate the relative" elevation-Hand azimuth of the reflector with respect to its frame and the airplane on Which'itis mountedat-the instant that the echo signal is -'-received.'

Preferably the wave guide system or conduit including the guide tube 89, and its associated fittings should be maintained under a clean and dry, normal atmospheric pressure so as to prevent electrical breakdown' when the aircraft on which the scanner is mounted, is operating in high altitudes. To insure this, a reciprocating pump (Fig. generally designated by the referencenumeral I2 and including a cylinder I72 is mounted on the upperface of the clutch bracket 3. Operatively disposed within the cylinder I72 is a piston I'I3to which is secured a connection rod I14. Journaled in a bearing housing I75 by means of ball bearings I76 and Ill is a shaft M8, to the upper end ofrwhich is secured a crank I I9, the-free end of the connecting rod E14 being journaled to a pin IBI mountedon the outer end of the crank I79. Fastened to the lower end of the shaft H8 is a worm gear I32 arranged to mesh,

with and be driven by the worm gear I31 which in turn is drivenby worm 58 formed on the shaft 5| (Fig. 2). Mounted over the outer end of cylinder I 72 is a pressure chamber I 83. provided with a spring loaded outwardly opening check valve set to open at normal atmospheric pressure. Communicating with the pump intake is the air filter and dehydrator I3 having an air intake provided with a suitable inwardly. opening spring-loaded check valve. The pump discharge communicates through a line 85 with the wave uide connection 86.

For the purpose of mountingthe scanner unit above described on .the nacelle of an airplane and for adjusting it for elevation and azimuth the main housing I is provided with opposed, laterally extending trunnion pinsv I9I and I92 (see Fig. 5) which carry the main load of the scanner, and the clutch bracket 3 is provided with a bracket I93 mounting a suitable altitude adjustment mechanism I94, for bore-sighting. Azimuth adjustment for bore-sighting can be provided for in. conjunction with one of the lateral trunnion pins. I9I and I92 in conjunction with suitable mountingbrackets provided on the nacelle.

Themotor 6 operates at 26 volts plus or minus 3.5 volts and delivers power to the scanner at 6,000 R. ,P.'M...p1us or ,minusLOOO R. P. M.. at loadsvarying from 400 to 600 watts and preferably. should be of the ball-bearing, air-cooled continuous duty type. At normal ambient temper-atureslapproximately 70 F.) the motor draws between 20 and 28 amperes and should drive the scanner at approximately 1,200 B. P. M. and nod cycles per minute.

Conveniently the reflector can be made 17 inches in diameter witha focallength of 5 inches, and r preferably is driven at 1,200.R. P. M.

a speed of.

In. operation, radio I frequency microwaves pass forwardly through: the substantially ;;air-tight wave-conduit or wave-guideand emerge from the I opposed windows oniuthe. lower face of the antenna head or cup TM; asgrings of electric energy- From the above description it will be observed that I have provided a scannin'g'unit wherein the reflector assemblyanditsrotating and oscillating mechanism can be readily brought into dynamic-balance;v whereinv the amplitude of nod ofv the refiectorcan be limited when the reflector is on target; wherein the wave-guideconduit can be maintained under any desired gaseous pressure; wherein means'including a potentiometer and a generatordriven in 'synchronism with the reflector, is provided by which the altitude and azimuth of the reflector'with' respect to the scanner frame can be determined; and which involves a relatively-simple construction.

I claim:

1. A scanning unitcomprising: a frame; a spindle journaled in said frame; a gear journaled on one end of said spindle for-rotation on an axis perpendicular to the axis of said spindle; a parabolic reflector fixed'to said gear and provided with a feed horn extending along the axis of the reflector; a waveguide communicating with the base. ofxsaid feed horn; a rack sleeve mounted within said spindle for reciprocatory movement with respect thereto, said sleeve being provided witha rackin= mesh with said gear; a potentiometer mounted on said frame and including a pair of resistance-coil sectors and a pair of contact arms arranged to traverse said sectors; meansresponsive to the movement of said rack sleeve for oscillating said contact arms; a generator mounted on said frame; and power means .for simultaneously rotating said spindle continuously, reciprocating said sleeve and rotating said generator continuously in the same direction.

2. A scanning unit comprising; a frame; a spindle journaled on said frame; a gear journaled on one end of said spindle with its axis perpendicular to the axis of the spindle; a parabolic reflector fixed to said gear for bodily movement therewith; a feed horn mounted on said reflector along the axis thereof; a rotatable, longitudinally slidable rack sleeve mounted on said frame and extending through said spindle, said sleeve being provided with a rack arranged to mesh with and oscillate said gear on the axis thereof; a Wave guidetube extending through said sleeve and communicating at its forward end with the base of said feed horn; a potentiometer mounted on said frame and including a pair of resistance-coil sectors and a pair of oscillating contact arms movable about a common axis and each arranged to traverse one of said sectors; means responsive to the sliding movement of said rack sleeve'for oscillating said contact arms; a two-phase generator in electric circuit with said resistance-coil sectors; and means for simultaneously rotating said spindle continuously, reciproeating. said rack sleeve and rotating said generator. continuously inthesame direction.

3..A scanning unitcomprisingz a frame; a

parabolic reflector swiveled to said frame for rotation about a first axis and simultaneous oscillation about a second axis intersecting said first axis at right angles thereto; a feed horn fastened to the apex of said reflector along the axis thereof; a wave guide tube communicating with the lower end of said feed horn; a pinion fixed to said reflector coaxial with said second axis; a rack mounted on said frame in mesh with said pinion for reciprocatory movement along a line parallel with said first axis; a potentiometer and a two-phase generator mounted on said frame, said potentiometer being in electrical circuit with said generator so as to control the a. lplitude of both of its phases; means for bodily rotating said reflector on said first axis and for simultaneously rotating said generator continuously in a single direction in synchronisrn there-- with; means for reciprocating said rack; and means responsive to the movement of said rack for actuating said potentiometer so as to vary the amplitude of both phases of said generator in synchronism with the oscillatory movement of said reflector.

4. A scanning unit comprising: a frame; a spindle journaled in said frame for rotation on its own axis; a gear journaied on one end of said spindle with its axis intersecting: the spindle at right angles thereto; a parabolic reflector fix-e to said gear for oscillation therewith and for rotation with said spindle; a feed horn mounted on said reflector along the axis thereof; a rack sleeve extending through said spindle and mounted for rotation therewith and for longitudinal movement with respect thereto; a rack mounted on said racl-z sleeve in mesh with said gear; a wave guide tube extending through said sleeve and connected with said spindle for rotation therewith; means for establishing communication between said wave guide tube and the base of said feed horn; a potentiometer mounted on said frame, said potentiometer including a pair of fixed coaxial resistance-coil sectors, a shaft mounted coaxial with said sectors, a pair of contact arms secured to said shaft and arranged to traverse said sectors and a pinion fastened to said shaft; a potentiometer rack slidably mounted on said frame in mesh with said pinion; a friction clutch mounted on said frame including a fixed member and a spring-loaded rotary member; a clutch shaft fastened to said rotary member; a crank fastened to said clutch shaft; a connection journaled at one end to the outer end of said crank and pivoted at its other end to said potentiometer slide rack; a bracket fixed at one end to said slide rack and having at its other end a rotary but longitudinally fixed connection with said sleeve rack; generator supported by said frame in electrical circuit with said potentiometer; and means for simultane-.

ously rotating said spindle, driving said clutch shaft and driving said generator.

5. A scanning unit comprising a frame, a

' spindle journaled in said frame, an antenna car- 10 oscillating said antenna, means for rotating said spindle and antenna, and variable drive means connected to said rack for reciprocating it at any selected one of a plurality of linear extents along said spindle.

6. A scanning device comprising a frame, a reflector mounted thereon for nodding about a nod axis, a spindle for said reflector operable to rotate the same about a spin axis intersecting said nod axis, means for rotating said spindle, means for nodding said reflector, said nodding means comprising a reciprocable member, and electrical means including a pair of oscillatable contact members actuated simultaneously by said reciprocable member, one of said contact members having a traverse indicative of the elevation of said reflector and the other of said contact members having a traverse indicative of the azimuth of said reflector.

7. A scanning device comprising a frame, a reflector mounted thereon for nodding about a nod axis, a spindle for said reflector operable to rotate the same about a spin axis intersecting said nod axis, means for rotating said spindle, means for simultaneously nodding said reflector, said nodding means comprising a reciprocable member including a rack, a potentiometer having electrically independent arms traversing electrically independent resistance windings, and a pinion engaging said rack and operable when said rack is reciprocated to oscillate said arms, one of said arms having a traverse indicative of the elevation of said reflector and the other of said arms having a traverse indicative of the azimuth of said reflector.

TOMLINSON I. MOSELEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,866,611 Affel July 12, 1932 2,151,917 Hyland Mar. 28, 1939 2,400,791 Tolson et al. May 21, 1946 2,407,305 Langstroth et al. Sept. 10, 1946 2,407,310 Lundy et al. Sept. 10, 1946 2,408,825 Varian et al. Oct. 8, 1946 2,409,183 Beck Oct. 15, 1946 2,410,666 Lock Nov. 5, 1946 2,410,827 Langstroth et al. Nov. 12, 1946 2,410,831 Maybarduk et al. Nov. 12, 1946 2,412,631 Rice Dec. 17, 1946 2,413,187 McCurdy et a1 Dec. 24, 1946 2,415,103 Langstroth et al. Feb. 4, 1947 2,415,678 Edwards Feb. 11, 1947 2,417,052 Beniofi Mar. 11, 1947 2,433,698 Hurst Dec. .30, 1947 OTHER REFERENCES Handbook of Maintenance Instructions, for AN/APS-G and AN/APS-GA Aircraft Radar Equipment; Bureau of AeronauticsU. S. Navy Dept; printing date: February 15, 1945; publication date: January 18, 1946; section I, paragraph 2, page 8, and section IV, paragraphs 16-17, pages 82, 93. 

